DE102021105143A1 - Electronic ignition device - Google Patents

Abstract

Electronic ignition device for triggering a pyrotechnic active system, such as a restraint system, for example an airbag gas generator, belt tensioner or buckle tensioner, comprising a first chamber in which a first ignition charge is arranged, which has a first primary explosive and a first ignition bridge for initiating a conversion of the first primary explosive and a second chamber in which a second ignition charge is arranged, which comprises a second primary explosive and a second ignition bridge for initiating a conversion of the second primary explosive, the first ignition bridge and the second ignition bridge being capable of being acted upon by the same electrical ignition signal, in particular ignition current or Ignition voltage, set up, and wherein the first and the second primary explosive and/or the first and the second ignition bridge differ from one another in such a way that the implementation of the first ignition charge is determined by an electrical ignition signal Time difference is faster than the implementation of the second squib.

Description

The invention relates to an electronic ignition device for triggering a pyrotechnic active system, such as a restraint system, in particular for vehicle occupant protection, for example an airbag gas generator, a belt tensioner or a buckle tensioner.

Electronic ignition devices are widely used in particular in restraint systems, for example for vehicle occupant protection. A restraint typically includes a pyrotechnic effect system. Pyrotechnic active systems are generally triggered by an ignition device that can be designed as an electrical ignition bridge. A pyrotechnic active system also includes a solid primary explosive and optionally a powdered propellant charge. The ignition device initiates the conversion of the primary explosive, so that a preferably inert gas is formed within a few milliseconds, causing a high pressure increase, which can be converted into a correspondingly rapid volume expansion of an airbag within about 20 to 30 milliseconds, for example.

In known airbag gas generators, two- or three-stage pyrotechnic restraint systems are often used in order to set an adjusted effective power level for filling the airbag as a function of the weight or size of a vehicle occupant. For example describes WO 2015 183 596 A2 a multi-stage ignition unit for airbag gas generators, with the help of which an airbag can be ignited in response to an initiating event in different stages with either high or low effectiveness or not at all. For this purpose, the maximum ignition pressure is varied. WO 2015 183 596 A2 describes an ignition controlled by means of a type of control feedback loop, in which an electrically operated ignition charge is operated with an electrical ignition energy below an ignition self-sustaining threshold value, so that ignition only takes place when electrical ignition energy is continuously applied.

In the known systems, it has been found to be disadvantageous that the effective power of the pyrotechnic restraint system can only be very roughly adapted to the actual requirements of the respective vehicle occupant, so that vehicle occupants in particular with a height or weight that clearly deviate from the specifications for deviates from the predetermined active power levels, do not experience ideal protection. Furthermore, it has been found to be problematic that misfiring can occur, for example, with too many or too few stages, which even impairs the protective effect for vehicle occupants with a stage-specific optimal body stature. There is also a problem in that multistage pyrotechnical restraint systems are generally installed less frequently due to their higher costs than pyrotechnical restraint systems without adjustability, which only develop the desired protective effect with regard to a specific occupant weight or a specific occupant size.

It is an object of the invention to overcome the disadvantages of the prior art, in particular a cost-effective, preferably particularly reliable, electronic ignition device that can be adjusted variably according to the requirements of occupants of all shapes and sizes for triggering a pyrotechnic active system, such as a restraint system, for example an airbag gas generator, belt tensioner or lock tighteners.

This object is solved by the subject matter of independent claim 1. Accordingly, an electronic ignition device is provided for triggering a pyrotechnic active system, such as a restraint system, in particular for vehicle occupant protection, for example an airbag gas generator, a belt tensioner or a buckle tensioner. The electronic ignition device comprises a first chamber in which a first ignition charge is arranged, which includes a first primary explosive and a first ignition bridge for initiating the conversion of the first primary explosive, and a second chamber in which a second ignition charge is arranged, which has a second primary explosive and a second squib for initiating a reaction of the second primary explosive. The primary explosives in the chambers are preferably completely separated from one another, so that in particular the conversion of the first primary explosive does not immediately trigger a conversion of the second primary explosive. In particular, the initiation of the first and second primary explosives are separate, but the action of the reactions of the two primary explosives are coupled, preferably often cumulatively or subtractively. The separation of the initiation of the first and second primary explosives may be due to the placement of the primary explosives in different chambers. It can be preferred that the first primary explosive and the second primary explosive have the same conversion temperature, in particular are the same. The first ignition bridge and the second ignition bridge are set up, for example as a series connection or preferably as a parallel connection, for the application of the same electrical ignition signal, in particular ignition current or ignition voltage.

Conversion generally refers to a chemical reaction in particular, during which a starting material or mixture, such as a primary explosive and/or a propellant charge, optionally in combination with other substances from the environment, reacts, for example oxidizes. During the reaction, new substances and/or mixtures can be formed, in particular gases. The reaction preferably takes place exothermally. Initiation generally refers to the start of the reaction.

A primary explosive has a relatively low initiation limit temperature and/or initiation limit energy, which is required for the primary explosive to react, i.e. to convert, preferably exothermically, in particular in a self-sustaining manner. Primary explosives can be provided in particular in combination with a propellant charge or the like, which has a higher initiation limit temperature and/or initiation limit energy than a primary explosive assigned to it.

According to the invention, it is provided that the first and the second primary explosive differ from one another in such a way and/or that the first and the second ignition bridge differ from one another in such a way that the implementation of the first ignition charge is faster than the implementation of the second by a time difference determined by the electrical ignition signal ignition charge. The two ignition bridges and/or the two primary explosives are preferably matched to one another in such a way that the power of the electronic ignition device can be continuously adjusted depending on the electrical ignition signal applied to both ignition bridges. In particular, the two ignition bridges and/or the two primary explosives are matched to one another in such a way that, depending on the electrical ignition signal applied to both ignition bridges, different maximum pressures can be adjusted, in particular continuously. The maximum pressure that can be achieved by an electronic ignition device decreases as the time difference between the implementation of the first and the second ignition charge increases.

Surprisingly, it has been shown that, contrary to the assumption that an improvement in the adjustability of the active power of an electronic ignition device necessarily causes a significant increase in the cost of the ignition device, both desired goals can be satisfied with the electronic ignition device according to the invention. It has turned out to be particularly advantageous that the characteristic curve of the electronic ignition device can be set structurally by the properties of the ignition pairs (primary explosive/ignition bridges), which allows cost-effective mass production. The properties of the ignition pairs can be described in a data sheet depending on the ignition signal, on the basis of which an occupant-specific ideal active power can be easily guaranteed. At the same time, the simple structural design of the ignition device according to the invention allows for a particularly robust and therefore less error-prone, reliable functionality.

According to one embodiment, the smaller the electrical ignition signal, in particular the ignition current or the ignition voltage, the greater the time difference. The size of the electrical ignition signal can be defined, for example, by the electrical power of the ignition signal or ignition signal power. In this case, in particular above an ignition signal threshold value, for example above an ignition signal power threshold value, the time difference can be approximately or equal to zero. In particular, above an ignition signal threshold value, the time difference between in particular the initiation of the conversion of the first and second ignition charge can be less than 1 millisecond, preferably less than 0.1 milliseconds, in particular less than 0.01 milliseconds.

ermittelt werden, wobei E die Initiierungsenergie, P die elektrische Zündsignal-Leistung des ersten oder zweiten Primärexplosivstoffs und t die zeitliche Dauer der Bereitstellung der Zündsignal-Leistung bis zur Initiierung der Umsetzung des ersten oder zweiten Primärexplosivstoffs bezeichnet. Der Index i steht für den ersten oder zweiten Zündsatz.For example, the first ignition bridge and the second ignition bridge can be configured to be operated with the same electrical power when the electronic ignition device is triggered, and the first and second primary explosive can be selected in a way that is coordinated with one another such that the first primary explosive has a lower initiation energy for initiating the Reaction required as the second primary explosive. According to this example, the time difference can be calculated using the equation $${\text{E}}_{\text{i}}={\text{P}}_{\text{i}}*{\text{t}}_{\text{i}}$$

be determined, where E denotes the initiation energy, P denotes the electrical ignition signal power of the first or second primary explosive and t denotes the duration of the provision of the ignition signal power up to the initiation of the conversion of the first or second primary explosive. The index i stands for the first or second ignition charge.

For example, if the required initiation energy E ₁ of the first igniter is less than the required initiation energy E ₂ of the second igniter, providing the same ignition signal power P ₁ =P ₂ will cause the initiation time t ₁ of the first igniter to be less than the initiation time t ₂ of the second ignition charge, and the time difference dt(dE) by which the first ignition charge is implemented faster than the second ignition charge, which depends on the difference in the required initiation energies. The required initiation energy of an interest rate can be largely adjusted by the material properties of the primary explosive. In particular, the first primary explosive and the second primary explosive are matched to one another in that they have different heat capacities, with the first primary explosive in particular having a lower heat capacity. Alternatively or additionally, the primary explosives are matched to one another such that the first primary explosive has a different, in particular lower, minimum reaction temperature than the second primary explosive.

$$\text{P}={\text{U}}^2/\text{R};$$

bzw. $$\text{P}=\text{R}*{\text{I}}^2$$

wobei U die Zündspannung, I den Zündstrom und R den elektrischen Widerstand der Zündbrücke bezeichnet. Der elektrische Widerstand einer Zündbrücke kann bestimmt sein durch deren Material und/oder Abmessungen. Der elektrische Widerstand der ersten und/oder zweiten Zündbrücke kann beispielsweise als Draht oder als dünne Metallschicht realisiert sein. Der elektrische Widerstand der ersten und/oder zweiten Zündbrücke kann beispielsweise Titan oder eine Chrom-Nickel-Legierung umfassen oder daraus bestehen. Zur unterschiedlichen Einstellung des elektrischen Widerstandes können die erste Zündbrücke und/oder die zweite Zündbrücke beispielsweise hinsichtlich ihres jeweiligen Volumens und/oder ihrer jeweiligen Geometrie spezifisch dimensioniert sein. Bei Bereitstellung eines Zündsignal mit derselben Zündspannung U für beide Zündbrücken kann beispielsweise durch die konstruktive Abstimmung der elektrischen Widerstände der ersten und zweiten Zündbrücke aufeinander bei ansonsten gleichen Eigenschaften der Zündbrücken bezweckt werden, dass infolge eines geringeren elektrischen Widerstands R₁ der ersten Zündbrücke als dem elektrischen Widerstand R₂ der zweiten Zündbrücke dem ersten Zündsatz eine entsprechend höhere Zündsignalleistung bereitgestellt wird.Alternatively or additionally, the ignition charges can be configured in such a way that the first ignition charge is provided with a different, preferably higher, ignition signal power than the second ignition charge by the electrical ignition signal. This can be done, for example, by the first ignition bridge and the second ignition bridge having different electrical resistances and/or thermal capacities and/or temperature characteristics, so that when the first ignition bridge and the second ignition bridge are acted upon by the same electrical ignition signal at the ignition charges, the electrical or thermal ignition signal power levels vary issue. The electric ignition signal power P can be described according to $$\text{P}=\text{u}*\text{I};$$

$$\text{P}={\text{<figure-callout id="2" label="u" filenames="DE102021105143A1\_0006.png" state="{{state}}">u</figure-callout>}}^2/\text{R};$$

or. $$\text{P}=\text{R}*{\text{<figure-callout id="2" label="I" filenames="DE102021105143A1\_0006.png" state="{{state}}">I</figure-callout>}}^2$$

where U denotes the ignition voltage, I denotes the ignition current and R denotes the electrical resistance of the ignition bridge. The electrical resistance of an ignition bridge can be determined by its material and/or dimensions. The electrical resistance of the first and/or second ignition bridge can be realized, for example, as a wire or as a thin metal layer. The electrical resistance of the first and/or second ignition bridge can include or consist of titanium or a chromium-nickel alloy, for example. In order to set the electrical resistance differently, the first ignition bridge and/or the second ignition bridge can be specifically dimensioned, for example with regard to their respective volume and/or their respective geometry. If an ignition signal with the same ignition voltage U is provided for both ignition bridges, the electrical resistances of the first and second ignition bridges can be matched to one another in terms of design, with the properties of the ignition bridges otherwise being the same, so that the electrical resistance R ₁ of the first ignition bridge is lower than the electrical resistance R ₂ of the second ignition bridge the first ignition charge is provided with a correspondingly higher ignition signal power.

Alternatively, when an ignition signal is provided with the same ignition current U for both ignition bridges, the electrical resistances of the first and second ignition bridge can be matched to one another in terms of design, with the properties of the ignition bridges otherwise being the same, so that as a result of a higher electrical resistance R ₁ of the first ignition bridge than the electrical resistance R ₂ of the second firing bridge the first firing charge is provided with a correspondingly higher firing signal power.

According to a simple example, the first primary explosive and the second primary explosive have the same required initiation energy E ₁ =E ₂ . Equation (1) results in a correspondingly higher initiation time t ₂ of the second ignition charge than the initiation time t ₁ of the first ignition charge when a greater ignition signal power P ₁ is provided at the first ignition charge and a smaller ignition signal power P ₂ at the second ignition charge. A time difference dt(dP) thus arises, by which the first ignition charge is implemented faster than the second ignition charge, which depends on the difference in the ignition signal powers provided.

According to an embodiment that can be combined with the previous one, the first ignition charge and the second ignition charge are configured in such a way that, below an ignition signal limit value, the first ignition charge is converted and the second ignition charge is not converted. In this case, the time difference approaches infinity. A lower ignition signal limit value can be defined as a lower limit current intensity and/or lower limit temperature. The ignition charges can be configured in such a way that when the ignition signal falls below the limit value, in particular the current limit, only the more sensitive of the two ignition charges triggers, which can be characterized, for example, by a lower initiation energy and/or by the fact that one of the respective Ignition bridge provided minimum temperature is mandatory for the initiation of the first or preferably second primary explosive. In particular, the first ignition charge and the second ignition charge are configured in such a way that, below a minimum ignition signal value, there is no conversion of either the first or the second ignition charge, it being possible for the minimum ignition signal value to be characterized as a minimum temperature of the respective ignition bridge, minimum current intensity and/or minimum Ignition signal performance (NoFire limit).

An embodiment that can be combined with the previous one provides that the first and the second firing bridge are connected to the same firing signal source for providing the electrical firing signal. A simple electrical circuit for activating the electronic ignition device can thus be implemented. Since the same ignition signal source provides both the first ignition charge and the second ignition charge with the same electrical ignition signal, faulty triggering of the ignition device with the wrong, significantly too high or too low effective system output is counteracted.

According to a further development, the first and the second firing bridge are electrically connected in parallel. In particular, according to this development, the ignition signal is an ignition voltage. According to an alternative development, the first ignition bridge and the second ignition bridge are electrically connected in series, with the ignition signal being an ignition voltage in particular.

In a further embodiment, which can be combined with the previous ones, the first primary explosive and the second primary explosive are matched to one another in such a way that the conversion of the first primary explosive takes place faster than the conversion of the second primary explosive, in particular independent of an equal or unequal initiation energy of the detonating charges. This means that even in the (theoretical) case that the initiation of the conversion of the first primary explosive and the second primary explosive takes place under the same triggering conditions and/or at the same time, a particularly complete conversion of the first primary explosive, for example for pressure development, is carried out more quickly and/or concluded as the particularly complete conversion of the second primary explosive. The first primary explosive may have a lower heat capacity than the second primary explosive. The first primary explosive may be composed of a composition having a faster reaction rate than the composition of the second primary explosive. Alternatively or additionally, the first primary explosive may have a lower reaction temperature threshold than the second. In particular, in an embodiment of an electronic ignition device with first and second primary explosives that react at different rates, the first ignition bridge and the second ignition bridge can be the same.

According to a further embodiment of an electronic ignition device, which can be combined with the previous ones, the first ignition bridge and the second ignition bridge are matched to one another in such a way that the electrical ignition signal heats the first ignition bridge more quickly to or above a conversion temperature threshold, in particular of the respective primary explosive. The first ignition bridge can have a different, preferably lower, electrical resistance than the second ignition bridge. Alternatively or additionally, the first ignition bridge can have a lower thermal capacity than the second ignition bridge. In particular, the first primary explosive and the second primary explosive have the same reaction temperature threshold. In particular, the first and the second primary explosive have the same composition. Alternatively, it is conceivable that the first primary explosive and the second primary explosive are matched to one another in such a way that the conversion of the second primary explosive takes place faster than the conversion of the first primary explosive. If the igniter is configured for earlier initiation of the first primary explosive by the first squib than initiation of the second primary explosive by the second squib, with subsequent faster conversion of the second than the first primary explosive, an opposing time shift can be used synergistically. Such a configuration can be advantageous, for example, in combination with the embodiment described above, in which a time difference of approximately or equal to zero is set.

For an electronic ignition device, with which a particularly wide range of different desired effective powers should be achievable, it can be advantageous to configure both the ignition bridges and the primary explosive for the first and second ignition charge so differently from one another that the first ignition charge compared to the second squib initiates both the implementation more quickly and implements the primary explosive more quickly.

In one embodiment of the electronic ignition device, which can be referred to as a cumulative embodiment and which can be combined with the previous ones, it is provided that the first chamber and the second chamber are separate from one another, with a first propellant charge in the first chamber and a first propellant charge in the second chamber a second propellant charge are arranged. The first chamber is connected to an expansion chamber via a first opening closed with a first shut-off cap. The second chamber is connected to the expansion chamber via a second port closed with a second shut-off cap. In particular, the first and the second propellant charge are of the same size and/or have the same composition. The expansion chamber can be implemented, for example, as a collection volume of an airbag or the like. In this cumulative design, the maximum expansion pressure that can be achieved with the propellant charges can be increased by the time offset between tween the ignition or initiation of the first propellant charge and the second propellant charge can be adjusted. For example, the maximum achievable expansion pressure can be dependent on the electrical ignition signal, in particular the ignition signal power, a lower maximum expansion pressure being achievable, for example, with the aid of a smaller electrical ignition signal, in particular with a smaller ignition signal power.

In an alternative embodiment of the electronic ignition device, which can be referred to as a subtractive embodiment and which can be combined with the other previous embodiments, except for the cumulative ones, the first chamber is connected to the second chamber via a through-opening which is closed by a first shut-off cap. The second chamber, in particular exclusively the second chamber, is connected to an expansion chamber via a second opening which is closed by a second shut-off cover. In particular, the first chamber is only connected to the second chamber, with the first chamber in particular not being directly connected to the environment and/or not directly to the expansion chamber. The primer in the first camera may include a first propellant. In such an embodiment, the implementation of the first igniter causes a modification of the implementation of the second igniter. Preferably, the first igniter weakens the effect of the second igniter as a function of the time difference determined by the electrical ignition signal.

According to a further development of the subtractive embodiment of the electronic ignition device, the first ignition charge comprises a passivation means for at least partially inactivating the (second) propellant charge arranged in the second chamber. The second propellant charge is not or only to a small extent, in particular less than 25%, preferably less than 10%, ignitable by the first primary explosive and/or the first propellant charge. The passivating agent in the first primer is designed to reduce the effect of the second propellant of the slower primer. In this alternative embodiment, the effect that can be achieved with the second propellant charge can be adjusted by the time offset between the ignition or initiation of the first and second ignition charges.

For example, the maximum achievable effect of the second ignition charge, in particular the maximum achievable propellant gas expansion, can be dependent on the electrical ignition signal, in particular the ignition signal power, it being possible, for example, using a smaller electrical ignition signal, in particular with a smaller ignition signal power, to achieve the maximum achievable effect of the second charge is more affected.

In a further development of the subtractive design of the electronic ignition device, a barrier is arranged in the second chamber, which shields the second primary explosive from the reaction of the first ignition charge and which is overcome by the reaction of the second ignition charge. When using a second primary explosive which is (not only slightly) flammable as a result of the reaction of the first ignition charge, in particular the first propellant charge or the first primary explosive, the barrier can serve as protection against undesired reaction of the second primary explosive when the first ignition charge is activated. A barrier can provide a useful security function, for example, when the two primers use the same primary explosive. The barrier is only opened in a targeted manner if the second ignition charge was activated using the second ignition bridge and the second primary explosive is converted as a result of its activation by the second ignition bridge.

According to another refinement of the subtractive embodiment, which can be combined with the previous ones, the passivating agent includes an inerting compound for wetting the (second) propellant charge. In particular, the inerting mass is an inerting fluid with a high thermal capacity and/or a high heat of vaporization. The initiating fluid can be, for example, an oil or glycerin. Alternatively or additionally, the inerting mass comprises at least one agent for chemically deactivating the second propellant charge, in particular the agent for chemically deactivating the propellant charge being designed with little and/or slow formation of propellant gas or without formation of propellant gas. It should be understood that the terms low and slow are to be understood in relation to the operational ignition of the second propellant by the second primary explosive. A deactivating agent can be implemented by a substance that chemically attacks and slowly destroys the second propellant. In this development, when the second ignition charge triggers the second propellant charge with a time delay, its original energetic mass is effectively no longer available and the effective power of the ignition device is consequently reduced.

Alternatively or additionally, in a further development of the subtractive design of an electronic ignition device, the passivating means can comprise a damping volume for at least partially accommodating the (second) propellant charge and/or a propellant gas formed from the second propellant charge which is produced by the reaction of the first ignition charge is connected to the second chamber, the expansion chamber being connected to the second chamber in particular by the reaction of the first ignition charge. Since the first ignition charge opens both the first shut-off cap and another, in particular the second shut-off cap, the second propellant charge can flow out partially or completely unignited before a second ignition occurs by activating the second ignition charge. In this development, the first ignition charge is set up to open a barrier between the second chamber and a larger volume, so that the second propellant charge is distributed in the larger volume. When the second primer finally ignites the second propellant, the ignition deteriorates due to the further distribution of the propellant. By providing the damping volume, less pressure develops when the second propellant is ignited than if the second propellant were ignited within the closed second chamber, so that it burns more slowly and thus has a significantly weaker effect, in particular an expansion effect. When using this further development of an electronic ignition device in an airbag gas generator, this would result in the airbag being inflated for a longer period of time, but with a lower compressive force being available, so that the airbag only optimally cushions smaller masses. In this development, an inerting compound and/or a deactivation means can be dispensed with.

In a development of an electronic ignition device according to a subtractive configuration, a cold-acting first propellant charge is arranged in the first chamber and a hot-acting second propellant charge is arranged in the second chamber. A cold-acting propellant charge preferably generates mostly (particularly at least 50%, preferably at least 70%) inert or inert gases such as nitrogen. In particular, cold-acting propellants can generate gases that are free of additional thermal energy-generating or releasing reactants. For example, AGAZ or low-particle detonators, for example based on nitrocellulose, can be considered as the cold-acting first propellant charge. The hot-acting propellant preferably comprises no more than 0.5% metal particles. A hot-acting propellant provides a propellant with a relatively low proportion of nitrogen (particularly less than 50%, preferably less than 25%). A hot-acting propellant charge preferably comprises further reactants, the further reactants promoting and/or providing redox reactions, for example. The other reactants can contribute in particular to the implementation of exothermic reactions when activated in the electronic ignition device. Inflammable substances such as B/KNO ₃ or those that contain many burning (metal) particles, such as Zr, Ti and/or CaSi, are particularly suitable as the hot-acting second propellant charge. The hot-acting propellant preferably comprises at least 3% metal particles. If the first and/or the second propellant charge is hot-acting, the expansion chamber into which the at least one hot-acting ignition charge is discharged can be referred to as the combustion chamber.

The amount of gas provided by the first ignition charge can be significantly lower, particularly in a subtractive embodiment or development, than the maximum amount of gas that can be provided by the second ignition charge (without deactivation). For this purpose, for example, the quantity of the first propellant charge in the first chamber can be less than the quantity of the second propellant charge in the second chamber, it being possible in particular for the first ignition charge to be designed without a propellant charge, so that the electronic ignition device only contains the contains so-called second propellant charge as the only propellant charge. Furthermore, it can be preferred that the gases provided by a reaction of the first ignition charge are free of hot particles such as burning metal powder.

The invention also relates to a gas generator for providing a variably adjustable active power, in particular to an airbag, a belt tensioner or a buckle tensioner, comprising an electronic ignition device as described above. The gas generator may alternatively be for driving a pyrotechnically powered fastening system, for example to drive a nail, say into a wall. With the help of the variable active power, the desired setting depth of the nail can be easily adjusted electronically. The gas generator preferably comprises a nitrogen-rich explosive. The gas generator preferably includes an explosive without further additives. In particular, the explosive is designed to decompose predominantly, i.e. at least 75% by weight, at least 90% by weight, or at least 99% by weight, into inert gas such as nitrogen and CO 2 when triggered. The gas generator preferably comprises exactly one or exactly two expansion chambers.

• 1 eine erfindungsgemäße elektronische Anzündvorrichtung;
• 2 eine andere erfindungsgemäße elektronische Anzündvorrichtung;
• 3 Zeit/Druck-Diagramme der Wirkung verschiedener elektronischer Anzündvorrichtungen;
• 4 ein Zündstrom/Zeitdifferenz-Diagramm einer erfindunsgemäßen Anzündvorrichtung; und
• 5 ein Zündstrom/Wirkleistungs-Diagramm einer erfindunsgemäßen Anzündvorrichtung.

Further properties, advantages and features of the invention become clear from the following description of preferred embodiments of the invention with reference to the accompanying drawings, above which:

• 1 an electronic ignition device according to the invention;
• 2 another electronic ignition device according to the invention;
• 3 Time/pressure diagrams of the action of various electronic ignition devices;
• 4 an ignition current/time difference diagram of an ignition device according to the invention; and
• 5 an ignition current/effective power diagram of an ignition device according to the invention.

In the following description of various configurations according to the invention with reference to the figures, the same or similar reference symbols are used for the same or similar components.

An electric ignition device according to the invention is denoted in the following in general by the reference number 1a or 1b.

The ignition device 1a, 1b comprises two chambers 11, 21 with a first or second ignition charge 13, 23 arranged therein of the respective primary explosive 15, 25. The second ignition charge 23 or both ignition charges 13, 23 can be equipped with a propellant charge 12a, 12b, 22a, 22b.

The first firing bridge 17 assigned to the first chamber 11 and the second firing bridge 27 assigned to the second chamber 21 are in the embodiments according to FIG 1 and 2 designed to be acted upon by the same ignition current I acting as an electrical ignition signal, in that the ignition bridges 17, 27 are connected in parallel to the same ignition signal source 7 which provides the electrical ignition signal.

When the ignition signal source 7 applies an ignition current I to the electronic ignition device 1a, 1b, this ignition current I flows through the first ignition bridge 17 and through the second ignition bridge 27 of the two ignition sets 13, 23. The ignition bridges 17, 27 form electrical resistances which heated by the flow of the ignition current I. The electrical ignition signal power of the ignition signal is partially converted into thermal energy by the ignition bridges. As soon as the temperature of the respective ignition bridge 17 or 27 reaches a minimum value sufficient to initiate the conversion or ignition of the primary explosive 15, 25 and/or after sufficient thermal energy has been provided to initiate the conversion by means of the ignition bridge 17, 27, the conversion of the primary explosive begins 15, 25. The reaction of the first or second primary explosive 15, 25 triggers (if present) an ignition of the respective associated propellant 12a, 22a, 12b, 22b.

According to the invention, the first ignition charge 13 and the second ignition charge 23 differ from one another. Differences between the ignition charges 13, 23 can be realized in the primary explosives 15, 25 or the ignition bridges 17, 27 or both of these ignition charge components. In addition, the second propellant 22a, 22b can differ from the first propellant 12a, 12b, or the ignition device 1a, 1b can only be equipped with a propellant 22a, 22b in its second chamber 21.

A cold-acting first ignition charge 13 can be referred to as an active charge. A cold-acting first active charge 13 can, for example, have a primary explosive 15 which, when triggered, primarily decomposes into an inert gas reaction, such as nitrogen and/or carbon dioxide. It is conceivable to design both the first and the second ignition charge 23 to be cold-acting. An ignition device 1a, 1b with cold-acting ignition charges is suitable, for example, for restraint systems, for example as an airbag gas generator or a belt or buckle tightener, as well as for pyrotechnically driven fastening systems, for example to shoot fastening nails into a wall, with the inventive adjustability of the ignition device by the electric Firing signal can advantageously be used to adjust the fastening system for different desired embedment depths or wall types.

1 shows a first embodiment of an ignition device 1a, in which the respective chambers 11 and 21, in which on the one hand the first ignition charge 13 and on the other hand the second ignition charge 23 are arranged, are separated from one another in order to avoid interactions. Both chambers 11, 21 each have an opening 14a, 24a, which is closed with a shut-off cover 16a, 16b. The shut-off cover 16a or 16b is designed to open as a result of the implementation of the respective ignition charge 13, 23, so that gas, such as propellant gas, can escape from the respective chamber 11 or 21 into an expansion chamber 3. As in 1 shown schematically, the openings 14a and 24a can lead from the different chambers 11, 21 to the same expansion chamber 3. Alternatively, it is conceivable to conduct the gas from the different chambers of the ignition device 1a into different, in particular separate, expansion chambers (not shown in detail).

The active power of the ignition device 1a can be adjustable, for example, between 50% and 100%, in particular if the first ignition charge 13 and the second interest rate 23 are of the same design with the exception of the ignition bridges 17, 27.

2 shows a second embodiment of an ignition device ib, which differs from the ignition device 1a according to FIG 1 differs essentially only in that only the second chamber 21 has an opening 24b to an expansion chamber 3 . The first chamber 11 can be connected to the second chamber 21 via a through opening 14b. A shut-off cover 16b can be provided in the through-opening 14b.

Furthermore, at the in 2 shown embodiment of the ignition device 1b in the through-channel 14b realized as an inerting mass 18 passivation agent can be provided. In particular, the inerting mass 18 can be implemented as an inerting fluid. This variant can be advantageous in particular if a passenger seat is expected to be occupied by a particularly small or low-weight person, such as a child, so that full inflation of an airbag would be undesirable.

The ignition of the first ignition charge 13 removes the shut-off cover 16b so that gas can pass from the first chamber 11 into the second chamber 21 and, if present, takes the inerting compound 18 or another passivation agent (not shown) with it. The passivation agent is set up to disrupt the ignition and, if applicable, conversion effect of the second ignition charge 23, so that its full potential cannot be deployed.

It may be sufficient as a passivation means that the chamber 21 is brought into fluid connection with a damping volume (not shown in detail) by the reaction of the first ignition charge 13 . The damping volume can be realized by the expansion chamber 3 . The (second) propellant charge 22b is carried along by the gases from the first propellant charge 13 and escapes at least partially into the damping volume due to the priority implementation of the first propellant charge 13 in terms of time 23 is specifically impaired in order to control the entire active power of the ignition device in this way. The active power of the ignition device 1b can be set between 20% and 100%, for example.

In accordance with the electronic ignition device 1b 2 the first and the second ignition charge 13, 23 are preferably matched to one another in such a way that the second ignition charge 23 quickly generates a higher pressure than the first ignition charge 13, in particular by only the second ignition charge 23 and not the first ignition charge 13 comprising a propellant charge 22b. When the ignition device 1b is activated with no or almost no time difference dt between the initiation of the conversions of the first and second ignition charges 13, 23, the gas generated by the two ignition charges 13, 23 flows from the second chamber 21 into the first chamber 11 and not vice versa , so that any inerting fluid 18 does not affect the second ignition charge 23.

Furthermore, the differs in 2 illustrated ignition device 1b compared to the ignition device 1a through the use of a barrier 28 in the second chamber 21, which shields the second primary explosive 23 against a reaction of the first ignition charge 13, ie the reaction of the first primary explosive 15 and possibly a first propellant charge 12b. The barrier 28 prevents a misfire of the second primer 23 caused by the conversion of the first primer 13. The barrier 28 is designed so that it is released by the pressure that is released by conversion of the second primary explosive 23 as a result of its ignition by the second primer bridge 27, is opened or bursts.

An embodiment as a subtractive electronic ignition device 1b is particularly suitable for the use of hot-acting second propellant charges 22b in combination with a first ignition charge with a cold-acting first propellant charge 12b (or without a first propellant charge). With such an ignition device 1b, sometimes not only the pressure is important, but also the availability of hot particles.

A hot-acting second ignition charge 23 is suitable, for example, to ignite further stages of pyrotechnics, for example a propellant charge for a larger system (not shown). Depending on the strength of the ignition of the further pyrotechnic stage of the larger system, its pressure generation can take place more quickly or more slowly. The hot-acting initiating charge 23 can be implemented, for example, with a primary explosive 15 and/or a propellant charge 22b, which is less nitrogen-folded and/or has additional reactants which, for example, carry out a redox reaction which, in particular, can be slower than the reaction of the conversion of the remaining primary explosive 15 or the rest of the propellant charge 22b. Additionally or alternatively, the hot-acting primer 23 may comprise very hot-burning metal powder.

3 shows various qualitative pressure/time diagrams to illustrate the effect of various electronic ignition devices. The units plotted along the axes are relative units. The diagrams are used to compare identically designed ignition devices. In the top and middle diagrams, the time-dependent pressure curves when using the same ignition device are shown side by side for comparison, either in a closed volume with the dot-dash line A or in an expanding volume with the solid line B. The bottom diagram shows the pressure profile of identical ignition devices according to the invention as a function of different electrical ignition signals and correspondingly different time differences dt.

In the top diagram of 3 shows the pressure curve as a result of the implementation of a single ignition charge in relative units. The triggering or initiation of the reaction takes place at time T=0. The reaction takes place in such a way that the pressure at time 1 reaches a maximum. Curve A corresponds to the pressure profile during ignition within a closed volume in which the pressure only drops slowly after the ignition charge has been converted, with the cooling of the combustion gases produced by the ignition charge being the decisive factor. The curve B corresponds to the pressure curve during ignition within an expanding volume that expands due to the pressure increase (such as an airbag). The pressure then drops again relatively quickly because the pressure causes the volume to expand and is thereby reduced.

In the middle diagram of 3 the pressure profile is shown in relative units as a result of a time-staggered implementation of a first and a second ignition charge. The first ignition charge is triggered at time T=0. The second ignition charge is triggered with a time offset of 1. Again, curve A corresponds to the pressure curve during ignition within a closed volume. In the closed volume, the electronic ignition device (which, for example, according to in 1 illustrated embodiment 1a can be realized) almost twice the maximum pressure compared to the effect of just a first ignition charge, regardless of the time lag between the triggering of the first ignition charge and the second ignition charge. This is not the case in the increasing volume, as can be seen from curve B of the middle diagram. Here the pressure drops again quickly as a result of the implementation of the first ignition charge. By the time the second ignition charge is ignited, a large part of the pressure increase brought about by the first ignition charge has already expired or been converted into an expansion effect. When the second squib is triggered, the maximum pressure generated will be less than the maximum pressure previously generated as a result of the deployment of the first squib. This is mainly due to the fact that the gases released by the second ignition charge flow into the already partially expanded volume.

The third diagram qualitatively shows the active power of several electronic ignition devices of the same type, which have been activated with different electrical ignition signals to bring about different time differences. The difference in the time difference between the five curves B1, B2, B3, B4 and B5 shown with different line deliveries is 0.2 each. The curves shown in the bottom diagram all relate to a pressure profile in an expanding volume. The curve B5 of the bottom diagram in 3 corresponds to curve B of the middle diagram.

The curve B1 shows the active power of an electronic ignition device 1a, 1b, in which two ignition charges 13, 23 have been subjected to an electrical ignition signal, which initiates the implementation of the first and second ignition charges 13, 15 at the same time or at least almost simultaneously. Due to the simultaneous ignition of the two ignition charges 13 and 23, a simultaneous implementation of the respective primary explosive 15 and 25 and possibly the associated propellant charges can be brought about.

In a cumulative embodiment of an ignition device 1a, for example according to FIG 1 be with respect to the bottom diagram in 3 it is assumed that the primary explosives and propellants of the first and second primers are of the same type. The pressure development effect of the two ignition charges acts cumulatively when the conversion is initiated at the same time, almost as if a single correspondingly larger ignition charge had been ignited.

The greater the time difference dt between the initiation of the implementation of the first ignition charge 13 and the second ignition charge 15, the more decisive for the maximum pressure is the implementation of only the first ignition charge 13. The curves B2 and B3 show an active power at which the second ignition charge 15 still influences the maximum pressure proportionally. Already in the case of curve B4, the maximum pressure is almost completely determined by the conversion of the first ignition charge 13, and the second ignition charge 15 causes almost no increase in the pressure maximum in comparison to ignition of only the first ignition charge 13.

In a subtractive embodiment of an ignition device 1b such as in 2 shown with respect to the bottom diagram in 3 it is assumed that the maximum of the pressure development effect according to curve B1 corresponds to the maximum possible effect of the second ignition charge 15 without being impaired by the first ignition charge 13. When the time difference dt between the initiation of the reaction of the first squib 13 and the second squib 15 is increased, this causes the passivation effect due to the reaction of the first squib 13 to affect the second squib 15 to an increasingly greater extent. The curve B2 corresponds to the pressure development effect of a second ignition charge 15, which has already been passivated to a certain extent, so that the maximum pressure reached turns out to be lower than the theoretically possible. In the case of curve B ₃ , the passivating agent activated by the first ignition charge 13 has already noticeably reduced the effect of the second ignition charge 15 .

The curves B4 and B5 can symbolize the pressure curve of a subtractive ignition device 1b, in which no inerting mass and no deactivation agent are used, but the conversion of the first ignition charge 13 has already opened the second chamber 21 to the expansion chamber 3, so that the propellant charge 22b from the second chamber 21 has at least partially escaped before the second ignition bridge 27 has completely implemented the second primary explosive 25 for igniting the propellant charge 22b. The maximum pressure occurring in the expansion chamber 3 is then limited to the effect of the first ignition charge 13.

4 shows a qualitative time delay/ignition signal characteristic. The ignition signal is represented here as ignition current I as an example. The hyperbolic characteristic curve shows the time difference dt between the initiation of the first ignition charge 13 and that of the second ignition charge 23. In general, the larger the ignition signal, the lower the time difference dt. If the ignition signal is greater than an ignition signal threshold value Is, there is practically no time difference (dt=o) between the initiation of the first and the second ignition charge 13, 23 to make out more. Below an ignition signal limit value I _G only the first ignition charge 13 is converted, but no longer the second ignition charge 23, so that the time difference dt increases to infinity.

5 shows a qualitative characteristic curve which represents the active power of the electronic ignition device according to the invention as a function of the electrical ignition signal, which is also represented here as ignition current I. If the ignition current I is less than a minimum ignition current Imin, neither the first ignition charge 13 nor the second ignition charge 23 are triggered. If the ignition current I corresponds at least to the minimum ignition current Imin, the first ignition charge 13 does not trigger the second ignition charge 23. For triggering the second ignition charge 23, the ignition current I must at least correspond to the limit ignition current I _G . The larger the ignition signal, the higher the effective power of the electronic ignition device. When the ignition current I reaches or exceeds the threshold ignition current I _S , at least 99% of the maximum possible active power of the electronic ignition device is delivered. By using an ignition current I in the range between the minimum ignition current Imin or the limit ignition current I _G on the one hand and the threshold ignition current I _S on the other hand, in particular in a range of the middle third between the limit ignition current I _G on the one hand and the threshold value Ignition current I _S on the other hand, the active power of the ignition device according to the invention can be finely adjusted in a predetermined manner.

The in the 4 and 5 The exemplary characteristic curves shown can represent the behavior of an electronic ignition device 1a according to the invention with the same type of primary explosive and the same type of propellant charge in the first chamber 11 and the second chamber 21 .

The features disclosed in the above description, the figures and the claims can be important both individually and in any combination for the implementation of the invention in the various configurations.

Reference List

1a, 1b

Electronic ignition device

3

expansion chamber

7

ignition signal source

11

first chamber

12a, 12b

first propellant

13

first primer

14a

first opening

14b

first passage opening

15

first primary explosive

16a, 16b

first shut-off cover

17

first ignition bridge

18

inerting mass

21

second chamber

22a, 22b

second propellant

23

second primer

24a, 24b

second opening

25

second primary explosive

26a, 26b

second shut-off cover

27

second ignition bridge

28

barrier

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• WO 2015183596 A2 [0003]

Claims (15)

Electronic ignition device (1a, 1b) for triggering a pyrotechnic active system, such as a restraint system, for example an airbag gas generator, belt tensioner or buckle tensioner, comprising: a first chamber (11) in which a first primer charge (13) is arranged, which comprises a first primary explosive (15) and a first primer bridge (17) for initiating a conversion of the first primary explosive (15); and a second chamber (21) in which a second primer charge (23) is arranged, comprising a second primary explosive (25) and a second primer bridge (27) for initiating a conversion of the second primary explosive (25); wherein the first firing bridge (17) and the second firing bridge (27) are set up to be acted upon by the same electrical firing signal, in particular firing current (I) or firing voltage; and wherein the first and the second primary explosive (15, 25) and/or the first and the second detonating bridge (25, 27) differ from one another in such a way that the conversion of the first detonating charge (13) is delayed by a time difference (dt) determined by the electrical detonating signal faster than the implementation of the second ignition charge (23). Electronic ignition device (1a, 1b) after claim 1 , the time difference (dt) being greater the smaller the electrical ignition signal, in particular the ignition current (I) or the ignition voltage, the time difference (dt) being approximately or equal to zero in particular above an ignition signal threshold value (I _s ). . Electronic ignition device (1a, 1b) after claim 1 or 2 , below an ignition signal limit value (I _G ), the implementation of the first ignition charge (13) takes place and the second ignition charge (23) undergoes no conversion. Electronic ignition device (1a, 1b) after claim 1 , 2 or 3 , wherein the first and the second firing bridge (17, 27) are connected to the same firing signal source (7) for providing the electrical firing signal. Electronic ignition device (1a, 1b) after claim 4 , wherein the first and the second ignition bridge are electrically connected in parallel, in particular the ignition signal is an ignition voltage. Electronic ignition device (1a, 1b) according to one of the preceding claims, wherein the first primary explosive (15) and the second primary explosive (25) are matched to one another in such a way that the conversion of the first primary explosive (15) takes place faster than the conversion of the second primary explosive (25), wherein in particular the first primary explosive (15) has a lower heat capacity and/or a lower conversion temperature threshold than the second primary explosive (25), in particular, the first ignition bridge and the second ignition bridge being the same. Electronic ignition device (1a, 1b) according to one of the preceding claims, wherein the first ignition bridge (17) and the second ignition bridge (27) are matched to one another in such a way that the electrical ignition signal heats the first ignition bridge (17) more quickly to or above a conversion temperature threshold, In particular, the first ignition bridge (17) has a lower electrical resistance and/or a lower heat capacity than the second ignition bridge (27), wherein in particular the first primary explosive (15) and the second primary explosive (25) have the same conversion temperature threshold, in particular are the same. Electronic ignition device (1a) according to one of the preceding claims, wherein the first chamber (11) and the second chamber (21) are separated from one another and wherein a first propellant charge (12a, 12b) is arranged in the first chamber (11) and a second propellant charge (22a) is arranged in the second chamber and wherein the first chamber (11) is connected to an expansion chamber (3) via a first opening (14a) which is closed by a first shut-off cover (16a), the second chamber (21) being connected to the expansion chamber (3) via a second opening ( 24a) which is closed with a second shut-off cover (26a), wherein in particular the first and the second propellant charge (12a, 22a) are of the same size and/or have the same composition. Electronic ignition device (1b) according to one of Claims 1 until 7 , wherein the first chamber (11) is connected to the second chamber (21) via a first through opening (14b) which is closed by a first shut-off cover (16b), the second chamber (21) being connected to an expansion chamber (3). a second opening (24b) is connected, which is closed with a second shut-off lid (26b). Electronic ignition device (1b) after claim 9 , wherein the first ignition charge (13) comprises a passivation agent for at least partially inactivating the (second) propellant charge (22b) arranged in the second chamber (21), wherein in particular the (second) propellant charge (22b) does not or only to a small extent through the first primary explosive (15) and/or the first propellant charge (12b) is flammable. Electronic ignition device (1b) after claim 10 , wherein a barrier (28) is arranged in the second chamber, which shields the second primary explosive from the reaction of the first ignition charge (13) and which is overcome by the reaction of the second ignition charge (23). Electronic ignition device (1b) after claim 10 or 11 , wherein the passivation means comprises an inerting mass (18) for wetting the (second) propellant charge (22b), wherein in particular the inerting mass (18) comprises an inerting fluid with a high thermal capacity and/or high heat of vaporization and/or in particular the inerting mass (18) comprises a Means for chemically deactivating the (second) propellant charge (22b), in particular with little and/or slow formation of propellant gas or without formation of propellant gas. Electronic ignition device (1b) according to one of Claims 10 until 12 , wherein the passivation means comprises a damping volume for at least partially accommodating the (second) propellant charge (22b), which is connected to the second chamber (21) by the reaction of the first initiating charge (13), in particular the expansion chamber (3) being connected to the second Chamber (21) is connected and/or the damping volume releases the (second) propellant charge (22b) from the second chamber (21) at least partially unignited. Electronic ignition device (1b) according to one of Claims 10 until 13 , A cold-acting first propellant charge (12b) being arranged in the first chamber and a hot-acting second propellant charge (22b) being arranged in the second chamber. Gas generator for providing a variably adjustable active power, in particular to an airbag, belt tensioner or buckle tensioner, comprising an electronic ignition device (1a, 1b) according to one of the preceding claims.

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